No doubt Raspberry Pi is the most popular single-board computer. If you need an elegant way to protect the naked circuit board, the following BramblePi3 Raspberry Pi case with GPIO slot should be able to meet your requirements.
This is a self-assembly wooden protective case designed for Raspberry Pi, and handmade by Nick from Germany. As we can see from the images, the Raspberry Pi case features gorgeous wooden construction, and is made out of birch plywood, while using laser cut finger jointed design you can easily assemble all the boards into an integral wood case by yourself without any tool. Moreover, the custom designed cutouts allow you access to the ports of your Raspberry Pi also including a GPIO slot for GPIO connection, apart from that, the engraved Raspberry Pi logo show your love to the credit card-sized single-board computer.
BramblePi3 Raspberry Pi case is priced at €14 EURO (approx $18 USD). If you’re interested, jump to Etsy for more details.